Roller guides for blackboards having adjustable panel bodies



Sept. 24, 1968 HHJENNY ETAL,

ROLLER GUIDES FOR BLACKBOARDS HAVING ADJUSTABLE PANEL BODIE Filed July 15, 1965 INVENTORS HANS JENNY MAX ALTMANN WQJWW/M United States Patent 3,402,483 ROLLER GUIDES FOR BLACKBOARDS HAVING ADJUSTABLE PANEL BODIES Hans Jenny, Niederurnen, and Max Altmann, Niederweningen, Switzerland, assignors to Palor AG, Niederumen, St. Gall, Switzerland Filed July 15, 1965, Ser. No. 472,132 1 Claim. (CI. 35-63) ABSTRACT OF THE DISCLOSURE Roller guides for the adjustment of blackboard panels, suitable particularly for large boards. The guide rollers are pivotably supported at the carrier arm of an angle lever whose resistant arm has a pivotably supported auxiliary lever. The space therebetween holds a spring which presses the auxiliary lever against an adjusting screw, and the pressure exerted is communicated to the guide roller through the carrier arm and the resistant arm of the angle lever. The guide roller thus is urged elastically into a groove in one of the supports which, together with the opposite support, takes up the horizontal pressure of the roller guide.

The invention relates to roller guides for blackboards having vertically adjustable panels and, more particularly, to roller guides which are readily adjustable and insure foolproof shifting without blocking of the panels.

For blackboards having a vertically adjustable panel body the faultless functioning of the roller guides is of greatest importance. If the blackboard can be shifted but difiicultly during the lessons or if it remains blocked, bothersome interruptions are inevitable, as in most cases the cause of the trouble cannot immediately be located and removed. This is particularly true as regards groups of blackboards fitted with large panels, arranged one behind the other and vertically independently adjustable, which have nowadays become indispensable in universities, re search institutes and similar institutions.

In general, vertically adjustable panels run between guide rollers, arranged by pairs, which are supported pivotably at their vertical outer edges, while running with their grooves along the guide rails of the blackboard frame; one of the roller couples is fixed locally, whereas the opposite couple of rollers is supposed to compensate irregular movements of the heavy panel body. In consideration of the total weight of, e.g., 400 kg. for panel and counter-weight, this alone represents a difficult task. Although it has been tried to solve the problem by means of adjustably supported roller guides, these have failed upon breakdowns during the lessons. Tests with automatically working balancing devices did not lead to satisfying results either.

The invention consists of a roller guide for blackboards, characterized by the fact that those guide rollers between which the panel to be adjusted moves and which are to regulate its movement are pivotably supported at the carrier arm of an angle lever. The resistant arm of the lever is fitted with an auxiliary lever, also pivotably supported, and the space between the former and the latter holds a coil spring, which presses the auxiliary lever against an adjusting screw, so that the pressure regulated by means of this screw which results from the coil spring is transferred onto the guide roller through the carrier arm and the resistant arm of the angle lever, pressing the guide roller elastically into the wedge-shaped groove of one of the supports which-together with the other support placed opposite-takes up the horizontal pressure of the roller guide.

3,402,483 Patented Sept. 24, 1968 The accompanying drawing shows a preferred embodiment of the design covered by the present invention.

In the drawings,

FIG. 1 is a view of the roller guide;

FIG. 2 is a top view of same;

FIG. 3'is a detail of FIGS. 1 and 2; and

FIG. 4 is a detail top view of same.

Referring now to these drawings, to the rear of panel 1, within the range of the vertical outer edge 2, a plate 3 is attached. Screwed to this plate is axle 4, serving as a revolving bearing for the angle lever, consisting of carrier arm 5 and resistant arm 6. A guide roller 8 runs on the carrier arm 5 about axle 7, engaging its running surface 9 into the wedge-shaped groove 10 of support 11 whichtogether with the opposite support not shown in the drawing-takes up the horizontal pressure of the roller guide. On top of resistant arm 6 an auxiliary lever 12 is disposed which also pivotably rests upon the angle lever axle 4. Between resistant arm 6 and auxiliary lever 12 a coil spring 13 has been provided, pressing the auxiliary lever 12 against an adjusting screw 14. The pressure generated by coil spring 13 and transferred to the resistant arm 6 and the carrier arm 5, is transmitted onto the guide roller 8 which is pressed elastically or by automatic compensation, respectively, into the wedge-shaped groove 10 of support 11. This support, together with. the opposite support not shown in the drawing, takes up the horizontal pressure of the roller guide.

As is usual and appropriate, at least two roller guides of the type covered by the present invention are attached to only one of the vertical edges, while on the opposite side locally fixed guide rollers sulfice.

In order to permit an easy and quick assembly of the roller guides, coil spring 13 is removed, and angle lever 5, 6 together with guide roller 8 are tilted downwardly, as shown by the dotted position of same in FIG. 1.

The roller guides covered by the invention assure a smooth and trouble-free run of the panels; furthermore they cover a large range of compensation, e.g. of 30 mm.

We claim as our invention:

1. A guide system for the adjustment of a vertically slidable blackboard panel comprising, in combination, a plate attached to the rear of said panel; an axle secured to said plate; an angle lever consisting of a carrier arm and a resistant arm, said lever rotating about said axle which serves as a bearing therefor; a guide roller running on said carrier arm and provided with an axle for rotating movement; a support having a wedge-shaped groove opposite said guide roller which engages in said groove; an auxiliary lever disposed on top of said resistant arm and pivotably resting on said lever axle; a coil spring disposed between said resistant arm and said auxiliary lever; an adjusting screw above said auxiliary lever, said auxiliary lever being pressed against said screw by said coil spring; the pressure generated by said coil spring being transferred to said resistant arm and to said carrier arm, and being transmitted to said guide roller which thereby is urged into said wedge-shaped groove.

References Cited UNITED STATES PATENTS 2,161,587 6/1939 Pettis 35-63 3,169,574 2/1965 Behlen 16-91 X 3,037,301 6/1962 Siepel 35-63 EUGENE R. CAPOZIO, Primary Examiner.

H. S. SKOGQUIST, Assistant Examiner. 

